A rock drill is a construction machine for operation of drilling blast holes in open-pit mining operation, and it mainly comprises a running gear, a frame, a power system, a rock drilling mechanism, an arm support mechanism, a dust removal mechanism, an electric control system, and so on. The arm support mechanism is a device for connecting the rock drilling mechanism with the frame, and supports the entire rock drilling mechanism. It is possible to adjust the position of the rock drilling mechanism through the action of the arm support mechanism, so as to realize drilling operation in different locations and states. The arm support mechanism can be classified into three types: a single arm, a telescopic arm, and a folding arm. As shown in FIG. 1, the conventional telescopic arm comprises a fixed arm 11, a movable arm 13 and a telescopic oil cylinder 12; the fixed arm 11 is sleeved on the movable arm 13, and the movable arm 13 is driven by the telescopic oil cylinder 12 to slide within the fixed arm 11, thereby realizing the telescopic action. Typically, four sliding blocks 16 are mounted on four surfaces of the outer side of the tail of the movable arm 13, and four sliding blocks 14 are mounted on the four surfaces of the inner side of the opening portion of the fixed arm 11. The sliding blocks 16 mounted on the movable arm slide along the inner side of the fixed arm 11, and the sliding blocks 14 mounted on the fixed arm enable the movable arm to conveniently slide along the inner side of the fixed arm. Adjusting pads 15 and 17 for controlling the height of the sliding blocks are provided between the sliding blocks and the movable arm and between the sliding blocks and the fixed arm so as to guarantee the gap between the movable arm and the fixed arm.
The telescopic arm of this structure has the following problems during the process of assembly and use:
(1) With the influence of manufacturing errors of the movable arm and the fixed arm, in order to ensure the movable arm to smoothly stretch and retract along the fixed arm, adjusting pads of different thicknesses need to be additionally mounted when the movable arm and the fixed arm are assembled, so that the gap between the sliding blocks and the movable arm and the gap between the sliding blocks and the fixed arm are uniform. However, such adjustment cannot be easily carried out in assembly, and it requires many times of trial assembly and thus takes time and effort.
(2) When the sliding blocks are worn, the gaps are enlarged, so it needs to completely disassemble the movable arm and the fixed arm and increase the adjusting pads or replace the sliding blocks. Therefore, the assembling and disassembling work are complicated.